CVE-2026-23240: Linux Kernel race condition (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: tls: Fix race condition in tls_sw_cancel_work_tx() This issue was discovered during a code audit. After cancel_delayed_work_sync() is called from tls_sk_proto_close(), tx_work_handler() can still be scheduled from paths such as the Delayed ACK handler or ksoftirqd. As a result, the tx_work_handler() worker may dereference a freed TLS object. The following is a simple race scenario: cpu0 cpu1 tls_sk_proto_close() tls_sw_cancel_work_tx() tls_write_space() tls_sw_write_space() if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask)) set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask); cancel_delayed_work_sync(&ctx->tx_work.work); schedule_delayed_work(&tx_ctx->tx_work.work, 0); To prevent this race condition, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync().

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Linux Kernel≥ 5.3.1 < 6.12.75 · ≥ 6.13 < 6.18.16 · ≥ 6.19 < 6.19.6 · 5.3

Remediation

Fixed in

Linux Kernel≥ 6.12.75

Patch & vendor advisories

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-23240 being actively exploited?

CVE-2026-23240 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.51%.

How severe is CVE-2026-23240?

CVE-2026-23240 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.51% probability of exploitation.

Which products are affected by CVE-2026-23240?

Affected products include Linux Kernel.

How do I fix CVE-2026-23240?

Upgrade affected software to a fixed version, for example Linux Kernel 6.12.75 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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